The present invention relates generally to a method of optical proximity correction in manufacturing a semiconductor device and, more particularly, to a method of correcting a mask pattern for a photolithography progress in manufacturing a semiconductor device.
Optical proximity correction (OPC) is a photolithography enhancement technique commonly used to compensate for image errors due to diffraction or process effects. To improve the resolution of the lithography process, certain types of illumination, for example, conventional illumination, annular illumination, QUASAR illumination, etc., may be introduced to improve the quality of lithography. The illumination condition is also important for OPC modeling. FIGS. 1A and 1B are schematic diagrams illustrating a method of using different illuminations to build an OPC model in prior art. Referring to FIG. 1A, annular illumination IL1′ may have an intensity of, for example, 1 and a radius of sigma-out/sigma-in of, for example, 0.9/0.7. Referring to FIG. 1B, the inner radius of annular illumination IL2′ may be reduced to 0.2 without changing the intensity so as to improve the accuracy of the OPC model for some kinds of patterns. However, the method may result in a trade-off between different patterns. For example, an OPC model thus built may be suitable for an “isolated” pattern without compromising a “dense” pattern, or vice versa. Therefore, it may be desirable to have a method of OPC to alleviate the trade-off issue.